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We conducted a long-term study to assess how tenure and territorial behaviors influence reproductive success among male Steller sea lions (Eumetopias jubatus (Schreber, 1776)). Copulations by males (n = 44) that maintained territories on a rookery in the Gulf of Alaska from 2001 to 2009 were observed using a remote video system. Approximately half of postpartum females copulated with a male in a different territory from where they gave birth. Nearly two-thirds of territorial males with known tenure were unsuccessful in copulating during their first year. Number of copulations for territorial males increased from acquisition year to year 2 with no change in subsequent years. Cluster analysis of tenure and territorial tactic variables for 15 males with observed lifetime reproductive success was used to describe multiple reproductive strategies. Characteristics of the two most successful strategies were the following: (i) males typically copulated in their first year, retained the same territories for 3-5 years, and occupied centrally located coastal territories where the highest percentage of females gave birth and (ii) males did not copulate until at least their third year and occupied peripheral territories with fewer births for a longer tenure of 7-8 years. Results indicated that lifetime reproductive success was not achieved solely by time on the breeding area; rather, it was achieved from a combination of tenure and territorial tactics. Key words: reproductive strategies, copulation, pinniped, Steller sea lion, Eumetopias jubatus, territorial, tenure. Nous avons realise une etude de longue duree afin d'evaluer l'influence des comportements territoriaux et de tenure sur le succes de reproduction des otaries de Steller (Eumetopias jubatus (Schreber, 1776)) males. Les copulations des males (n = 44) qui ont maintenu des territoires dans une roquerie du golfe d'Alaska de 2001 a 2009 ont ete observees a l'aide d'un systeme de televideo. Environ la moitie des femelles post-partum ont copule avec un male dans un territoire autre que celui dans lequel elles ont mis bas. Pres des deux tiers des males territoriaux dont la tenure etait connue n'ont pas reussi a copuler durant leur premiere annee. Le nombre de copulations pour les males territoriaux augmentait de l'annee d'acquisition a la deuxieme annee, les annees subsequentes ne montrant aucun changement sur ce plan. L analyse topologique de variables reliees aux tactiques territoriales et de tenure pour 15 males pour lesquels le succes de reproduction a vie etait etabli sur la base d'observations a ete utilisee pour decrire differentes strategies de reproduction. Les caracteristiques des deux strategies donnant le meilleur succes de reproduction sont les suivantes : (i) les males copulent typiquement durant leur premiere annee, conservent le meme territoire pendant de 3 a 5 ans et occupent des territoires cotiers centraux oU le plus grand pourcentage de femelles met bas, et (ii) les males ne copulent pas avant leur troisieme annee au plus tot et occupent des territoires peripheriques comptant moins de mises bas, pendant une plus longue tenure de 7 a 8 ans. Ces resultats indiquent que le succes de reproduction a vie n'est pas seulement lie au temps passe dans l aire de reproduction, mais depend plutot d une combinaison de tactiques territoriales et de tenure. [Traduit par la Redaction] Mots-cles : strategies de reproduction, copulation, pinnipede, otarie de Steller, Eumetopias jubatus, territorial, tenure., Introduction A major objective of animal behavior studies is to understand the adaptive significance of behavioral variation (Mayr 1974). Within the same species, multiple reproductive strategies have evolved as a [...]

Several major breeding areas have been defined for the South American sea lion (Otaria flavescens) along the Atlantic Ocean including the Uruguayan and Patagonian coasts. Together with a documented and severe reduction in population sizes caused by commercial hunting in the last century, these areas show opposite population trends. While Patagonian populations are recovering since hunting ceased, Uruguayan populations are declining. In this context, population genetic structure and genetic diversity were studied for the first time with both nuclear (microsatellites) and mitochondrial (control region) markers together. Alternative scenarios were found for both markers. While mitochondrial marker showed geographically structured populations, the nuclear loci showed a lack of geographical structure. These opposite patterns in genetic structure could be explained by female phylopatry and high male dispersion. The reduction in population size caused by commercial hunting did not leave a detectable footprint of bottleneck at the genetic level., Author(s): Matías Feijoo [sup.1] , Enrique P. Lessa [sup.1] , Rocío Loizaga de Castro [sup.2] , Enrique A. Crespo [sup.2] Author Affiliations: (1) grid.11630.35, 0000000121657640, Sección Evolución, Facultad de Ciencias, [...]

We used quantitative fatty acid signature analysis (QFASA) to predict the long-term diet of New Zealand (NZ) sea lions (Phocarctos hookeri) incidentally caught in the NZ arrow squid (Nototodarus spp.) fishery. The QFASA model used fatty acid (FA) profiles based on 82 blubber samples of NZ sea lions bycaught between 2000 and 2006. First, the model was optimized by a series of simulations for which 1 model parameter--6 different sets of calibration coefficients (CCs) from different pinniped species and feeding regime, 2 sets of FAs, and the consideration of individual prey values, or mean prey values--varied each time. The best-fit parameters were those giving the lowest Kullback--Liebler distance values. Second, these parameters were used in a model to estimate the diet of NZ sea lions. QFASA was highly sensitive to the set of CCs applied. Across years the most important prey estimated with the best-fit CCs were southern arrow squid (Nototodarus sloani, 18-28% mass), hoki (Macruronus novaezelandiae, 10-27% mass), rattails (Macrouridae, 7-27% mass), and possibly scampi (Metanephrops challengeri, 1-19% mass). Despite the uncertainty on the accuracy of the match between the best-fit CCs used and the true FA metabolism of NZ sea lions, the variation of prey estimated among years was highly consistent with the trends of commercial catches during the same period, providing some confidence in the present QFASA predictions. The most important estimated prey were demersal species living mainly at depths >200 m that NZ sea lions encounter on the slopes of the Auckland Islands shelf. Our study emphasized the importance of these areas for bycaught NZ sea lions over the 1st half of the lactation period. DOI: 10.1644/09-MAMM-A-299.1. Key words: dietary methods, feeding ecology, pinniped

Body size is an important determinant of the diving and foraging ability in air-breathing marine vertebrate predators. Satellite-linked dive recorders were used during 2003-2004 to investigate the foraging behavior of 22 male California sea lions (Zalophus californianus, a large, sexually dimorphic otariid) and to evaluate the extent to which body size explained variation among individuals and foraging strategies. Multivariate analyses were used to reduce the number of behavioral variables used to characterize foraging strategies (principal component analysis, PCA), to identify individually based foraging strategies in multidimensional space (hierarchical cluster analysis), and to classify each individual into a cluster or foraging strategy (discriminant analysis). Approximately 81.1% of the variation in diving behavior among individuals was explained by three factors: diving patterns (PC1), foraging effort (PC2), and behavior at the surface (PC3). Individuals were classified into three distinct groups based on their diving behavior (shallow, mixed depth, and deeper divers), and jackknife resampling of the data resulted in correct group assignment 86% of the time. Body size as an independent variable was positively related to dive duration and time spent ashore and negatively related to time at sea, and it was a key parameter in PC2 used to classify the three distinct clusters. Differences among individual-based foraging strategies probably were driven by differences in body size, which enabled larger animals to dive deeper and forage more efficiently by targeting different and perhaps larger prey items. The occurrence of foraging specializations within a species and age class has implications for quantitative modeling of population-level predator-prey interactions and ecosystem structure. Key words: body size; California sea lion; diving behavior; foraging strategy; individual specialization; predator--prey interactions; sexual dimorphism; Zalophus californianus.

A sample of 834 female New Zealand sea lions (Phocarctos hookeri), which were aged and measured, was obtained between 1998 and 2001. In addition, the reproductive histories of 505 marked females from the Auckland Islands were recorded from 1998 to 2005. These data sets were used to investigate growth and reproductive rates. Length and weight ranged from 134 to 197 cm and 49 to 156 kg, respectively. A Gompertz growth model best described growth and predicted that females attained 90% of asymptotic length (161.7 cm) and weight (112.0) at ages 4 and 11 years, respectively. No significant differences were found in growth rates among years, nor between the 2 major breeding colonies in the Auckland Islands. Females reproduced between the ages of 3 and 26 years, with evidence of reproductive senescence starting at age 23 years. Although females up to age 28 years were observed, no females over 26 years were recorded as reproductive. Age-specific reproductive rate p(x) increased rapidly between ages 3 and 7 years, reached a plateau between ages 7 and 23 years, and then declined rapidly after age 23 years. Mean observed reproductive rate was p[(x).sub.3-28] = 0.67 (SE = 0.01). This is the 1st robust estimate of reproductive rate for this species, is consistent with rates reported for other sea lions, and is considerably lower than assumed rates used in recent population modeling for this species. This calls into question the current method for estimating levels of sustainable bycatch. Low growth and reproductive rates are consistent with a population that is occupying a marginal foraging environment. These factors, along with a recent significant decline in pup production, suggest that current management is insufficient to ensure population stasis, let alone meet the statutory goal of recovery. DOI: 10.1644/09-MAMMA-110R.1. Key words: growth, New Zealand sea lion, Phocarctos hookeri, reproduction [c] 2010 American Society of Mammalogists

Ontogenetic differences between males and females result in sexual dimorphism, but this process is poorly understood in the majority of mammalian taxa. Sexual dimorphism is particularly extreme in the otariids (Carnivora: Otariidae), and to examine the origin, structure, and temporal patterns of otariid morphological diversity, we locus here on 3 otariid species: Arctocephalus australis (southern fur seal), Callorhinus ursinus (northern fur seal), and Otaria byronia (southern sea lion). Our aims are to compare the ontogeny of skull shape across species, and to evaluate the ontogeny of sexual dimorphism, testing the hypothesis that dimorphism arises by extrapolation of a shared ontogeny to the larger sizes that are characteristic of males. We found that dimorphism increased over ontogeny but was not due solely to allometric extrapolation, because different rates of development were found in some species. Specifically, the relationships between changes in shape and size increase were different between sexes in A. australis and O. byronia, but equal in C. ursinus. It is possible to implicate heterochrony in the origins of the modifications undergone during the ontogeny of males and females of A. australis and O. byronia, considering the differences in the rates of development between the sexes of both species, but it is certain that allometric repatterning also is involved in these. Key words: dimorphism, geometric morphometrics, ontogeny, Otariidae, skull

Pinniped blubber supports multiple functions including thermoregulation, reproduction, and buoyancy. Although blubber depth is frequently used as an indicator of health, the effect of sample site and seasonality are rarely taken into account. We monitored blubber depth via imaging ultrasound at 10 sites monthly for 1 year in 2 adult Steller's sea lions (Eumetopias jubatus) and 3 adult harbor seals (Phoca vitulina). Blubber of harbor seals was thicker and more variable than blubber of sea lions, and was thickest in winter. Changes in harbor seal blubber at all sites tracked variation due to season and mass. Sea lion blubber changed with mass only at specific sites, with no seasonal effect. The differing effects of season, mass, and location on the body must be carefully considered in both species before any interpretation of condition. Key words: blubber, Eumetopias jubatus, harbor seal, Phoca vitulina, Steller's sea lion, ultrasound

Abstract: A technique was developed to estimate morphometrics and body mass of Steller sea lions (Eumetopias jubatus) using three-dimensional (3D) photogrammetry. 3D photogrammetry reduces many of the problems associated with [...]

This research examines the foraging energetics and diving behavior of the Australian sea lion, Neophoca cinerea. We examine whether the foraging ecology of the Australian sea lion is typical for an animal that has evolved to exploit benthic habitats. Such a strategy is in marked contrast to those utilized by some seabirds and other pinnipeds that feed in the midwater, where travel and search components of the time at sea become more important. Onshore and at-sea field metabolic rates (FMR) were measured using doubly labeled water in lactating sea lions at Kangaroo Island, South Australia, during the winter of 1988 (early lactation, breeding season 1) and the summer of 1990 (early lactation, breeding season 2). Dive behavior was also measured with dataloggers during these seasons, as well as in the summer of 1991 (late lactation, breeding season 2). The foraging behavior of Neophoca cinerea indicated that it works hard to exploit benthic habitats in the waters around its breeding site. Sea lions maximized time spent at or near the benthos, with 61% of each dive and 35% of their time at sea being spent at the deepest 20% of the dives. The dive pattern was characterized by almost continuous diving when at sea, with 57.9% of their time at sea spent at depths [greater than or equal to] 6 m, and dive rates of 10.7 dives/h. Mean surface intervals (1.0-1.9 min) accounted for only 42% of mean dive durations (2.2-4.1 min). Mean dive depths ranged from 41.5 m to 83.1 m, with maximum dives ranging from 60 m to 105 m. The energetic costs of this strategy are high when compared with those of other otariids: the mean at-sea FMR was 7.05 [+ or -] 0.99 W/kg. We report seasonal variability in foraging energetics and dive behavior that is likely to be sensitive to regional oceanography, the maintenance costs of female sea lions and their offspring, and the distribution and behavior of their prey. Further, we note that Australian sea lions are functionally adapted to benefit from benthic foraging strategies because their larger size and insulating blubber convey an advantage over the generally smaller sympatric fur seals that would have a decrease in air/ fur insulation with compression at deeper depths and would experience greater water infiltration of the fur with longer dives. Key words: aerobic dive limit; Australian sea lion; benthic foraging; diving behavior; doubly labeled water; foraging ecology; foraging energetics; fur seals; interannual variability; Neophoca cinerea; sea lions; seasonality.

A recent taxonomic review of the Otariidae, based on morphometric techniques applied to skulls, revealed a number of specimens with cranial morphology divergent from typical otariid species. The specimen considered in this paper was a large adult male otariid with cranial morphology most similar to the California sea lion, Zalophus californianus, but differing from it in significantly greater condylobasal length and rostral and palatal structure. Discriminant function analyses were applied to compare the cranial morphology of the anomalous specimen with those of 7 otariid taxa: the Steller sea lion, Eumetopias jubatus; the southern sea lion, Otaria byronia; the California sea lion, Z. californianus californianus; the Galapagos sea lion, Z. c. wollebaeki; and the presumed-extinct Japanese sea lion, Z. c. japonicus. Results suggest that the aberrant skull was that of a hybrid between Z. californianus and O. byronia. Key words: hybrid, morphometrics, Otaria byronia, sea lion, skull, Zalophus californianus

Fur seals, sea lions, walruses and true seals all belong to the aquatic mammals known as pinnepedia, which means fin-footed, referring to the characteristic flippers at the end of their limbs. True seals lack external ears, have non-rotating rear flippers and are unable to lift themselves from the ground. Sea lions and fur seals have external ear flaps, rotating hind flippers and are capable of far more agility on land. All have a body shape that is streamlined for swimming. The walrus, which constitutes its own family within the pinnepedia, can weigh 3,000 lbs and has long canine teeth called tusks.

The fitness, pup mortality and the quality of the Baltic gray seal (Halichoerus grypus) females while breeding on land, as well as in ice are discussed. The analysis shows that the breeding success of the Baltic gray seal females considerably decreases due to the decreasing ice coverage, hence increasing the chances of quasi-extinction.

Diving animals offer a unique opportunity to study the role physiology in limiting behavior. An important component of the physiological capability of any diving animal is it's aerobic dive limit (ADL). The ADL has only been measured in a few species. The goal of this study was to estimate the aerobic dive limit from measurements of body oxygen stores and at sea metabolism. This calculated ADL was compared to measurements of diving behavior of individual animals of three species of otariids, the Antarctic fur seal, Arctocephalus gazella, the Australian sea lion, Neophoca cinerea and the New Zealand sea lion, Phocarctos hookeri. Antarctic fur seals dove well within the cADL. In contrast, many individuals of both sea lion species exceeded the cADL. Australian and New Zealand sea lions dove 1.4 times longer than the cADL. The tendency to exceed the cADL was correlated with the dive pattern, of individual animals. In both Antarctic Fur Seals and Australian sea lions, deeper diving females made longer dives that approached or exceeded the cADL (P [is less than] 0.01, r2 = 0.54). Australian and New Zealand sea lions with longer bottom times also exceeded the cADL to a greater degree. The two sea lions forage on the benthos while the fur seals feed shallow in the water column. It appears that benthic foraging requires these animals to reach or exceed their aerobic dive limit.

The prevalent hypothesis for the >80% decline of Steller sea lions (SSLs) in western Alaska is that changing prey quality and/or quantity have prevented sea lions from meeting their energetic demands, thus creating a deficit, or nutritional stress. This may be particularly true in younger animals which experience the high energetic demands associated with growth. When energy intake is insufficient to meet daily energetic demands, some animals are able to compensate by limiting their energy expenditures. The most common physiological response to limited food intake is a lowering of resting metabolic rate (RMR) known as metabolic depression. Given observed reductions in RMR in captive SSLs fed a low energy diet, the potential significance of metabolic depression in juvenile free-ranging SSLs was examined via open flow respirometry. Free-ranging animals were captured from western stocks in Prince William Sound (PWS, n =30) and the Central Aleutian Islands (AL, n=16) and from the eastern stock in Southeast Alaska (SE, n=43). RMR was measured in animals aged 2, 5, 8, 11, 14, 20 and 26 months at ambient air temperatures (-6-18 [degrees]C). Standard morphometrics, blubber depth, and total body fat stores were measured for an estimate of body condition at each location. Mean RMR ranged from 11.0 to 32.3 MJ [d.sup.-1] across all aged animals, and as expected, increased with increasing body mass. Although air temperatures varied between capture sites, similar temperatures existed between PWS and SE locations, allowing direct comparisons of RMR, blubber depth, and total body fat stores between similarly aged animals. Our data indicate no evidence of metabolic depression in western stock animals.

Foraging strategies of air-breathing marine vertebrates develop as as a dynamic relationship between physiological performance, energetic requirements and characteristics of environment. Within this context, different phylogenetic groups vary in their physiological capabilities. One of the primary determinants of physiological capacity is the aerobic dive limit (ADL), which is influenced by the rate at which total body oxygen stores are consumed while diving. Differences in ADL correlate with variations in foraging behavior. For example, true seals (Family Phocidae) have greater oxygen stores than sea lions and fur seals (Family Otariidae) and as a group, true seals dive longer and often deeper than sea lions and fur seals. While the pattern between members of each family has been well documented, variation within a family has not been as carefully examined. Inspection of the diving behavior and ADL within the sea lions and fur seals shows that there is considerable variation in physiological capability. Further, these differences correlate with the diving behavior observed in the wild. We measured the total body oxygen stores (muscle myoglobin and blood hemoglobin concentration and blood volume) of 7 otariids, Australian sea lion, and fur seal, the northern fur seal, the Hookers sea lion, the Sub-Antarctic fur seal, the Antarctic fur seal and the California sea lion. Oxygen stores varied from a low of 38.1 ml O2/kg in Antarctic fur seals to a high of 58.6 ml O2/kg in a population of deep diving California sea lions. There was a highly significant relationship between mean dive duration measured for each species in the field and their mean total oxygen stores.

The western population of the Steller sea lion (Eumetopias jubatus) experienced a pronounced population decline in the 1970's-90's. The initial decline is thought to have involved reduced quantity or quality of prey, but it is unclear what factors are now preventing population recovery. To enable noninvasive assessment of physiologic stress of free-living sea lions, we validated a fecal glucocorticoid assay using ACTH (adrenocorticotropic hormone) injections in four captive Steller sea lions. All four showed pronounced elevations in fecal glucocorticoids after ACTH injection, indicating that assay results reflect adrenal activity. We assayed 206 scats from Steller sea lion haul-outs in the declining (Gulf of Alaska) population, and 265 scats from the stable (Southeast Alaska) population. Diet was determined from hard parts recovered from scats, and dietary energy content was estimated from known caloric densities of prey. Both populations had significantly higher fecal glucocorticoid concentrations and significantly lower dietary energy density in winter compared to summer. During winter, sea lions in the declining population consumed a richer diet, and had significantly lower fecal glucocorticoids, than sea lions in the stable population. No significant differences were seen between glucocorticoid levels of the two populations in summer. Glucocorticoid differences were noted in summer between mature males, mature females and immature animals. Though many questions remain to be answered, these results suggest that the Gulf of Alaska population is not currently suffering from nutritional stress, and that other factors such as orca predation may now be more important in preventing population recovery.

Female Juan Fernandez fur seals, Arctocephalus philippii, undertake long foraging trips during lactation, resulting in intersuckling intervals that are among the longest ever recorded for a mammal. We collected 44 samples of milk from this fur seal to determine if milk would have a high concentration of fat, as predicted from the hypothesized relation between milk concentration and intersuckling interval. Milk of Juan Fernandez fur seals contained on average 55.1% dry matter, 41.4% fat, 11.9% protein, 1.2% sugar, 0.7% ash, 780 mg/kg calcium, and 840 mg/kg phosphorous. Content of fat and energy were the highest reported for a fur seal or sea lion (Family Otariidae) in the 1st month of lactation. Energetic content was 17.95 kJ/g, and 74% of fatty acids were unsaturated. Data from seven species and subspecies of otariid seals indicated that length of foraging trip explained 66% of the variation in content of fat in milk among taxa. Content of energy in milk of otariid seals also was explained primarily by the duration of trips to sea. Key words: Arctocephalus philippii, Juan Fernandez fur seal, lactation, maternal strategies, pinnipeds, Chile